A continuously variable transmission of this kind is constructed with, e.g., clamping a disc-shaped roller between a pair of discs arranged opposed to each other. The portions of the pair of discs where is the outer side from a predetermined radius has an arcuate plane congruent with the arc centered on the center point of those opposed planes of those discs, and such arcuate plane is leading to circumferential direction. The plane thus incurved three-dimensionally is a toroidal plane. The toroidal planes functions as a rolling face and the roller is clamped therebetween. The roller is disc-shaped member and its sectional figure along the in-depth direction of the outer circumferential portion is congruent with the arcuate figure of the rolling face of the discs. Accordingly, the roller is rotated by means of rotating one of the discs, and the other disc rotates sequentially. Then, the roller is inclined to move the radial position of the contact portion against one of the discs, i.e., the radial position from the center axis of the disc outward, and also to move the radial position of the contact portion against the other disc to inner circumferential side, so that the gear ratio corresponding to the proportion of the radii of each contact portions is accordingly set.
Transmission of the torque in this toroidal type continuously variable transmission is executed according to the load (pressure) to thrust the disc and the power roller; therefore, bigger torque is transmitted, bigger clamping force to clamp the power roller becomes, and the amount of the heat generated between the disc and the power roller becomes larger in consequence. Surface hardening treatment is provided on the surface of the disc in order to bear a big clamping force. However, the condition similar with the tempering is generated when the surface temperature of the disc is risen by the heat evolution arises from the transmission of the torque. As a result, abrasion, separation or the like is occurred on the toroidal face of the disc in connection with degrading of the hardness of the disc surface, and its durability is thereby deteriorated. Also, in general, transmission of the torque between the disc and the power roller is executed by the shearing force generated therebetween without contacting those directly. However, as mentioned above, viscosity of the oil film is deteriorated when the temperature rises, and as a result, slippage could occur and there is a possibility to cause a faulty transmission of the torque.
Accordingly, in the toroidal type continuously variable transmission, it is preferable to execute cooling aggressively on the portion where the transmission of the torque is generated, i.e., the surface of the disc or the like. A device for that purpose is disclosed in e.g., Japanese Patent Laid-Open 11-280876 heretofore. Taking generation of slippage due to decreasing of the traction force arise from the temperature rise of the traction drive portion as a contact portion between the disc and the roller into consideration, the device disclosed on this Laid-Open is constructed of; an oil reservoir portion provided on the end portion of inner circumference of the disc; and an oil passage formed on a post (protrusion) protruding from inner circumferential face of the casing to the center portion; in order to feed lubricating oil which is fed to the oil reservoir portion through the oil passage, to the toroidal face with defusing by means of centrifugal force that accompanies the rotation of the disc. With this construction, the lubricating oil spreads overall from the inner circumferential side of the toroidal face with flowing to the outer circumferential side, and the heat is drawn in the meantime. Accordingly, temperature rise of the disc is thereby suppressed or prevented.
However, if the oil reservoir portion as disclosed in the aforementioned Laid-Open is to be arranged with being faced on the inner circumferential end of the disc, the oil reservoir portion has to be arranged with being fixed on the outer circumference of the input shaft or the output shaft, because, in the toroidal type continuously variable transmission, an input shaft or an output shaft is arranged along the center axis of rotation of the discs with penetrating those. In order to construct such arrangement, the oil reservoir portion is to be held by some member leading from the inner face of the casing to the center portion. However, a fixing member has to be interposed between the rotary members and so that the structure becomes complicated, as a result, there is a possibility to make manufacturing and assembling difficult.
Also, the device disclosed in the aforementioned Laid-Open has to be structured with inserting inner circumference end portion of the disc from the both side of the oil reservoir portion in the axial direction, and the structure of the oil reservoir portion has to be so-called ring shaped with opening its both right and left side. Therefore, it is rather difficult to conserve the lubricating oil and it is necessary to flow a large amount of the lubricating oil continuously, in order to feed the lubricating oil sufficiently. In other words, to control the amount of the lubricating oil is rather difficult, and there are disadvantages such as unnecessary flow of large amount of the lubricating oil, and subsequent unnecessary waste of the motive energy. This invention has been conceived noting the aforementioned technical problem and has an object to provide a toroidal type continuously variable transmission which can feed the lubricating oil without excess and deficiency with simple structure, to the face where the transmission of the torque is generated, such as the toroidal plane.